This non-provisional application claims priority under 35 U.S.C. §119(a) on Korean Patent Application No. 2006-68501 filed on Jul. 21, 2006 which is herein incorporated by reference.
1. Field of the Disclosure
Exemplary embodiments of the present invention relate to a novel metal nanoparticle and a method for forming a conductive pattern using the same. More particularly, exemplary embodiments of the present invention are directed to a novel metal nanoparticle, which is prepared by forming a self-assembled monolayer including a terminal reactive group on the surface thereof, and introducing a functional group capable of being removed by the action of an acid or a base into the terminal reactive group, and a method for forming a conductive pattern using the same. The self-assembled monolayer is built up of a thiol, an isocyanide, an amine, a carboxylate or a phosphate compound having the terminal reactive group, or is built up of a thiol compound and the like having no terminal reactive group followed by introducing the terminal reactive group thereinto.
2. Description of the Related Art
Since a nanosized material shows various electrical, optical and biological properties depending on its one-, two- and three-dimensional space structures and orders, extensive research on the nanosized materials is actively underway worldwide in such diverse application fields as nano-devices, optical information devices, bioelectronic devices, and the like. Especially, among such nanosized materials, a metal nanoparticle has a very wide industrial applicability. This is because when a metal is provided in a nanosized particle in a bulk condition, its surface area is remarkably increased and only a few atoms exist in the nanosized particle, which exhibits unique catalytic, electric, photoelectric and magnetic properties. Further, since the metal nanoparticle having conductivity through an electrical conductive mechanism such as charge transfer or electron transfer has a significantly large specific surface area, a film or a pattern including the metal nanoparticle can exhibit high conductivity although it contains only a small amount of such metal nanoparticle. In addition, if its particle size is regulated to the range from 3 to 15 nm so as to enhance the packing density, electron transfer at an interface between the metals is more greatly facilitated, thereby further improving the conductivity.
Meanwhile, with the advancement of the electronics industry in recent years, research into the development of a highly conductive film or pattern composed of various raw materials is actively progressing. When using the metal nanoparticle, there are several advantages with it being possible to produce a film or a pattern having a high conductivity without the use of a sputtering or an etching process that requires a complicated condition such as the use of a high vacuum or high temperature, and it also is possible to form a conductive pattern in a transparent condition to visible light by regulating the particle size. However, it is very difficult to control and arrange microparticles uniformly in order to apply the metal nanoparticle to a film or a pattern.
One of the methods for effectively arranging the metal nanoparticle that is well-known in the art is a method using a self-assembled monolayer in which compounds having a functional group with chemical affinity to a certain metal are molecularly arranged on the surface of the metal nanoparticle. This method can structurally control the thickness of the self-assembled monolayer to be in the range from 10 to 40 nm. In this regard, Paul E. Laibinis et al. suggest that a self-assembled monolayer is formed by arranging n-alkanethiol on the surface of a metal, and Yu-Tai Tao discloses that a self-assembled monolayer is formed by arranging n-alkanoic acid, dialkyl disulfide or dialkyl sulfide on the surface of a metal such as gold, silver, copper, aluminum, or the like.
However, when using the metal nanoparticle including the well-known self-assembled monolayer, there are several problems such as difficulties in the regulation of the space regularity or molecular orientation, unstability, defects, surface ordering control, and aggregation of the metal nanoparticle when fabricated into a thin film. For the above reasons, therefore, it is impossible to easily prepare a large area film or an ultramicro pattern which has even limited industrial applicability.
Consequently, there is an increasing demand for the development of a new type of a self-assembling nano-construct which is capable of forming a large area film or an ultramicro pattern by using a metal nanoparticle.